Automatic breaker with coil adjustable to effect current limiting or electrodynamic blowoff compensation

ABSTRACT

AN AUTOMATIC BREAKER INCLUDES A MOVABLE CONTACT SYSTEM AND A STATIONARY CONTACT SYSTEM OPERATIVELY ASSOCIATED WITH ONE ANOTHER. THE STATIONARY CONTACT SYSTEM IS CONSTITUTED AS A SERIES COIL HAVING BOTH A MOVABLE AND STATIONARY MEMBER. THE STATIONARY MEMBER IS ADJUSTABLY SUPPORTED SO THAT IT CAN BE TURNED 180* FROM A FIRST POSITION TO ALTER THE ELECTRODYNAMIC FORCES EXERTED BY THE STATIONARY MEMBER ON THE MOVABLE MEMBER. IN THIS RESPECT THE STATIONARY MEMBER WHEN IN THE FIRST POSITION CONSTITUTES THE SERIES COIL AS A CURRENT LIMITER AND WHEN TURNED 180* THEREFROM CONSTITUTES THE SERIES COIL AS A COMPENSATOR.

Filed Feb. 28, 1968 1971 G. F. MITSKEVICH ETAL 3,555,471

AUTOMATIC BREAKER WITH COIL ADJUSTABLE TO EFFECT CURRENT 1 LIITING 0RELECTRODYNAMIC BLOWOFF COMPENSATION '4 Sheets-Sheet 1 3,555,471 CTCURRENT ATION Sheets-Sheet 2 Jan. 12, 1971 G. F. MITSKEVICH AUTOMATICBREAKER WITH COIL- ADJUSTABLE TO EFFE LIMITING OR ELECTRODYNAMIC BLOWOFFCOMPENS Filed Feb. 28, 1968 4 FIG. 2 v

H V/A Jan. 12, 1971 rrs v c ETAL 3,555,471

AUTOMATIC BREAKER WITH COIL ADJUSTABLE TO EFFECT CURRENT LIMITING ORELECTRODYNAMIC BLOWOFF COMPENSATION Filed Feb. 28. 1968 4 Sheets-Sheet 3Z 22 331735 3536 F/G5 as I 4 Jan. 12, 1971 s v c ETAL 3,555,471

AUTOMATIC BREAKER WITH COIL ADJUSTABLE T0 EFFECT CURRENT LIMITING ORELEUTRQDYNAMIC BLOWQFF COMPENSATION Filed Feb. 28, 1968 4'Sheets-Sheet4.

United States Patent AUTOMATIC BREAKER WITH COIL ADJUSTABLE T EFFECTCURRENT LIMITING 0R ELECTRO- DYNAMIC BLOWOFF COMPENSATION GennadyFeodosievich Mitskevich, Vladislav Yakovlevich Guschin, Jury NikolaevichVorontsov, Vladimir Avramovich Boguslavsky, Anatoly Mikhailovich Bela-Belov, Viktor Izrailevich Rakhlis, Viktor Revoldovich Oktyabrev, OlegIvanovich Artsybashev, and Fedor Andreevich Vakhomchik, Kharkov,U.S.S.R., assignors to Vsesojuzny Nauchno-Issledovatelsky I Proektno-{(JoSnsStrIgktorsky Institut Electroapparatov, Kharkov,

Filed Feb. 28, 1968, Ser. No. 709,101

Int. Cl. H01h 77/10 US. Cl. 335-195 Claims ABSTRACT OF THE DISCLOSURE Anautomatic breaker includes a movable contact system and a stationarycontact system operatively associated with one another. The stationarycontact system is constituted as a series coil having both a movable andstationary member. The stationary member is adjustably supported so thatit can be turned 180 from a first position to alter the electrodynamicforces exerted by the stationary member on the movable member. In thisrespect the stationary member when in the first position constitutes theseries coil as a current limiter and when turned 180 therefromconstitutes the series coil as a compensator.

The present invention relates to automatic breakers intended forshort-circuit and overload protection in electrical units, as well asfor occasional operational switchings of AC and D-C circuits and, moreparticularly, to automatic breakers intended for the operation in bothcurrent-limiting (quick-action) and selective protection duties. 1

Known in the art are automatic breakers, e.g. triplepole breakers,comprising a control mechanism, a maximum current release gear, andmovable and stationary systems of contacts in each of the poles, eitherof the contact systems being provided with arcing horns arranged underarcing suppressors.

Also known are automatic breakers, e.g. triple-pole selective breakerswith electrodynamic compensators, as well as automatic breakers ofincreased switching capacity with built-in quick-break fuses.

Each of these known automatic breakers has its own designation;correspondingly, they all vary in design, overall and settingdimensions, which fact complicates their manufacture and createdifficulty in arranging them in switching devices. Other disadvantagesare a low switching capacity, inconvenience in use since after cuttingoff short-circuit currents, the requirement of a change of burned outfuses, thus leading to time waste in the equipment operation and makingimpossible the remote control of automatic breakers, and also theprovision of a fuse unit increases overall dimensions.

It is an object of the present invention to provide an automatic breakerusable both as a current-limiting and selective switch, requiring only aminor rearrangement of the components of its contact system.

According to this and other objects, in an automatic breaker with asystem of movable and stationary contacts in each of the poles,according to the invention, the system of stationary contact isfashioned as at least a double-Wound series coil serving as anelectrodynamic device, and consists of a movable part functioning as astationary contact, and of a stationary part. The point of "iceconnection of these parts of the series coil and their shape areselected such as to permit a turn of the stationary part of said coil inrelation to its longitudinal axis, provided the position of its movablepart insuring normal closure of the contacts remains invariable. Theturn of the stationary part of the series coil varies the direction ofelectrodynamic impact on the movable part of said coil and, dependingupon the position of its stationary part, permits the use of the coilboth as a current limiter in the current-limiting version of the breakerand as a compensator in its selective version.

The movable and stationary parts of the series coil may be U-shaped,while it is feasible that the point of connection of these parts bebetween the sides of the U-shaped stationary part of the coil.

It is feasible that the point of connection of the U- shaped stationaryand movable parts of the series coil be equidistant from the sides ofthe U-shaped stationary part.

In order to increase the electrodynamic impact on the movable part ofthe series coil, one of the sides of the latter may be arranged insidethe stationary part of the coil, while the other side is arranged on itsexterior.

The movable part of the coil may have an elongated end serving as anarcing horn for the stationary contact.

For the connection of an outer circuit, the stationary part of theseries coil may have a lead-out arrangement symmetrically with respectto the sides of said part, one of which sides may support the stationarypart within the breaker.

It is feasible to divide the movable part of the series coil, whichserves as stationary contact, into at least two longitudinal portionswhereon the contacts are secured.

In order to synchronize the motion of the above-said longitudinalportions, it is feasible that they be mechanically interconnected bymeans of, for example, a roller.

It is feasible that said longitudinal portions be connected to oneanother with a clearance so as to permit their self-setting when thebreaker contacts are closed.

In order to preclude the interwelding of the arcing horns of thestationary contacts when moving towards each other, the surfaces of saidhorns facing each other, may be provided with projections arranged belowthe working surface of the horns.

The automatic breaker may be fitted with a device for insuring contactpressure and automatic lowering of the working contacts of thecompensator.

It is feasible to make the device for insuring the contact pressure andautomatic lowering of the working contacts of the compensator in theform of a spring, a bushing and a rod, the latter passing inside saidspring and bushing and having a nut on one of its ends and a head on theother end, and movable inside the bushing secured in the automaticbreaker body. It is feasible that the spring of said device be restingagainst the nut at one of its ends and against the bushing at the otherend.

Other objects and advantages of the present invention will be moreapparent from the description of a specific embodiment thereof,reference being had to the appended drawings, wherein:

FIG. 1 shows diagrammatically a general view of the automatic breaker,according to the invention;

FIG. 2 is a series coil of the automatic breaker, which is used ascurrent limiter, side view;

FIG. 3 is a series coil of the automatic breaker, which is used as acompensator, side view;

FIG. 4 is a top view of FIG. 2;

FIG. 5 is a series coil of the automatic breaker, which is used ascompensator with a device insuring the contact pressure and automaticlowering of the working contacts, side view;

FIG. 6 shows a joint A in FIG. 5, on an enlarged scale; and

FIG. 7 (a, b and c) is the diagram of the current fiow through thecontact systems of the automatic breaker, according to the invention.

Enclosed in a plastic body 1 (FIG. 1) of the automatic breaker are: abreaker-controlling mechanism 2 coupled with a handle 3, a maximumcurrent release gear for switching otf the automatic breaker in case ofemergency conditions of a protected circuit, a system 5 of movablecontacts and a system 6 of stationary contacts. The systems 5 and 6 arearranged in each pole of the automatic breaker beneath an arcing deviceconsisting of steel plates 7 secured in insulation walls 8 and afire-extinguishing grid 9.

The system 5 of movable contacts comprises a working contact 10 and acurrent-conducting contact holder 11 which is coupled with a lead-outbusbar 13 by means of a flexible connection 12. The contact holder 11 isprovided with an arcing horn 14.

By means of the controlling mechanism 2 the contact holders 11 of eachpole of the automatic breaker are coupled with the handle 3 intended foroperating the automatic breaker.

The system 6 of stationary contacts is made as a doublewound series coilsewing as an electrodynamic device.

The series coil functioning as a stationary contact consists of movableand stationary parts 15 and 16 respectively, both U-shaped. The point ofconnection of said U-shaped movable and stationary parts is arrangedbetween the sides of the stationary part so that one of the U-shapedsides of the movable part 15 of the coil lies within the stationary part16, whereas the other side is placed on the outer side thereof. Thislargely increases the electrodynamic impact on the movable part 15 ofthe coil, as the occurrence of arcing in the contact systems of theautomatic breaker results in a current circuit forming an additionalcoil (FIG. 70). In this case, the point of connection of the movable andthe stationary parts 15 and 16 respectively, of the series coil isequidistant from the sides of the stationary part so that the size g isequal to the size g (FIGS. 2, 3, and 5). Such an embodiment of themovable and stationary parts 15 and 16 respectively, of the coil and theselection of the point of their connection permit, provided the positionof the movable part 15 remains invariable, the turning of the stationarypart 16 of the coil by 180 in relation to its longitudinal axis and theuse of the series coil as both a current limiter (FIG. 2) and acompensator (FIGS. 3 and 5), as this turn of the stationary part 16 ofthe series coil changes the direction of electrodynamic impact 'on itsmovable part 15.

One of the ends of the U-shaped stationary part of the series coil has alead-out 17 serving as a connection for the outer conductors and issymmetrical or equally spaced from both of its sides so that thedistance B is equal to the distance B (FIGS. 2, 3 and 5), while itsother end is connected to the movable part 15 of the coil by means of aprop 18 and a current-leading hinge 19.

The symmetrical arrangement of the lead-out 17 in relation to the sidesof the stationary part 15 permits a setting of the stationary part 16,after its turn by 180, which insures a permanent and stable contact ofthe movable part 15 with the working contact 10.

The movable part 15 of the series coil functioning as stationary contacthas a working contact 20.

When the series coil is used as a current limiter (the current-limitingversion of the automatic breaker, FIG. 2), its stationary part -16 issecured to the body 1 of the automatic breaker with a side having thelead-out 17, in case said series coil is employed as a compensator (theselective version of the automatic breaker), it is fastened with itsother side to whose end the prop 18 (FIGS. 3 and 5) is attached. Bothsides of the U-shaped stationary part 16 of the series coil are providedwith apertures 21 insuring the support of said coil by the automaticbreaker body 1 by means of screws 22.

In case the series coil is employed both as a current limiter (FIG. 2)and as a compensator (FIGS. 3 and 5), its movable part 15 remains in aposition permitting the normal shortening of the working contacts 10 and20.

The movable part 15 of the series coil with its contact 20 is dividedinto two longitudinal parts, each having an elongated end 23 serving asan arcing horn.

In case the series coil is used as a compensator, its divided movablepart 15 reduces the electrodynamic repulsion of the contacts 10 and 20owing to a greater number of contact points.

In case the series coil is used as a current limiter, the division ofthe movable part 15 insures a more stable magnitude of the operationcurrent of the current limiter. Thus, with current flowing through thecoil, its movable part 15 is influenced by the sum of two forces, i.e.,the stable force of the electrodynamie circuit induced by the seriescoil, and the unstable force of the contacts repulsion. The division ofthe movable part 15 of the series coil helps decrease the unstablecomponent of the sum of the forces and thus decrease the spread of theoperation current of the whole series coil circuit. Furthermore, thedivision of the movable part 15 of the series coil permits a bettercentering of the arc whose point of bearing tends to travel along a slotdividing the arcing horns 23, as well as improves the conditions of heatemission in the case of prolonged current flow. The division of themovable part 15 of the series coil may occasionally cause irregulardistribution of the current in it, which brings about an asynchronousdisconnection of the contacts 20. In order to insure the synchronoustravel, the divided movable part 15 of the series coil has a connectionby means of a roller 24 (FIG. 4) passing through apertures 25. Thisconnection is made with a clearance, thus insuring a selfsetting of theworking contacts 20 when the automatic breaker is in ON-position.

In order to prevent the interwelding of the arcing horns 23, and tomaintain the clearance therebetween when moving towards each other underthe action of the electrodynamic forces emerging when the arc travelsalong them, the sides of the arcing horns 23 are provided withprojections 26, laterally engageable with one another which are belowthe working surface of the arcing horns 23 along which the are bearingpoint travels.

Electric contact in the current-leading hinge 19 coupling the movableand stationary parts 15 and 16 respectively, of the series coil iseffected simultaneously in two ways: through the conjugated surfaces ofthe divided movable part 15 of the series coil and the prop 18, as wellas through the surface of a current-conducting axis 27 and the surfaceof the apertures in the movable parts 15 of the series coil and the prop18.

When the surfaces of the current-leading axis 27 come into contact withthe surfaces of the openings in the movable part 15 of the series coiland the prop 18, the contact pressure is effected by means of a spring28 (FIGS. 2 and 3), whose one end rests against the movable part 15 andthe other end bears againt the stationary part 16 of the series coil.

When the conjugated surfaces of the movable part 15 of the series coiland the prop 18 come into contact, the contact pressure is effected bymeans of a spring 29 (FIG. 4), whose one end rests against the head ofthe currentconducting axis 27, and the other rests against the movablepart 15 of the series coil.

In order to insure stable contact, the surfaces of the divided movablepart 15 of the series coil and the prop 18 carry straps 30 made of amaterial possessing high conductivity and mechanical strength (forinstance, metal ceramics on a sliver basis).

The contact pressure of the working contacts 10 and 20 of the automaticbreaker used as both a current limiter and a compensator (in currentlimiting or selective variants) is effected by means of a spring 31(FIGS. 2

and 3), one of whose ends rests against the movable part 15 of theseries coil, and the other end rests against a screw 32 screwed into ashoe 33 fastened to the body 1 of the automatic breaker whose turnregulates the contact pressing.

The provision of the series coil as a compensator insures highelectrodynamic stability of the contact system of the automatic breaker.However, said electrodynamic stability can be made still higher bylowering of the working contacts so as to compensate the springingeffect of the parts of the control mechanism 2, but this reduces theswitching capacity of the automatic breaker.

The electrodynamic stability of the working contacts of the automaticbreaker may be increased by employing, instead of the spring 31 insuringonly contact pressure, a device 34 (FIG. which, in addition to theprovision of contact pressure, automatically lowers the working contactswhen strong currents flow through the series coil, without affecting theswitching capacity of the automatic breaker.

The device 34 comprises a rod 35 (FIG. 6) passing through a Spring 36insuring contact pressure and a bushing 37. Said bushing 37 is screwedinto the shoe 33 secured in the body 1 of the automatic breaker. The rodhas, on one of its ends, a head 38 provided inside the bushing 37 and anut 39 on the other end. By its one end, the spring 36 rests againt saidbushing 37, and against the nut 39 by the other end. The extent ofcompression of the spring 36 conditions the force of contact pressure.By screwing the bushing 37 into the shoe 33 fastened in the body 1 ofthe automatic breaker, it is possible to adjust a clearance 6 (thenormal lowering of the contacts) which is chosen to be smaller than aclearance 5, (FIG. 5) (the lowering of the contacts taken with regard toautomatic increase).

The device 34 is an independent unit which can be unscrewed from thebody 1 of the automatic breaker and which allows the adjustment of thecontact pressure outside the automatic breaker by way of fastening thenut 39 on the rod 35.

In order to actuate the automatic breaker, the handle 3 (FIG. 1) istransferred into position C. As a result, the control mechanism 2rapidly shifts the contact holders 11 and instantly closes the workingcontacts and 20 (FIGS. 2, 3 and 5), said closure being independent ofthe speed of the travel of the handle 3.

All this results in a closed electric circuit.

The flow of the current through the series coil used as a currentlimiter causes the emergence of electrodynamic forces which act to turnthe movable part of the series coil, fastened to which is the workingcon- 5 tact 20, toward a pointer F (FIGS. 2 and 7b).

However, the electrodynamic circuit induced by the series coil which isused as a current limiter, as well as means for compressing the spring31, are selected such that the turn of the movable part 15 takes placeonly after the current has reached a certain magnitude, i.e. the currentof electrodynamic setting. The magnitude of this current is greater thanthe magnitude of the current causing the operation of the maximumcurrent release gear 4.

The same spring 31 insures contact pressure when the working contacts 10and (FIG. 2) are closed.

In case of emergence of short-circuit current in a protected circuit,stronger than the current of electromagnetic setting of the series coilused as a current limiter, under the action of electrodynamic forcesinduced in said coil, the movable part 15 of the series coil begins toturn at a high speed around the axis 27 breaking the contacts 10 and 20(FIG. 70) before the operation of the control mechanism 2. The emergingarc restricts the growing of the short-circuit current and prevents itfrom reaching its maximum.

With the arc on the horns 14 and 23, the current flowing through thelatter forms an additional coil largely increasing the electrodynamiceffect which results in a higher speed of breaking the contacts 10 and20.

As the arc travels along the arcing horns 14 and 23, it passes into thearcing suppressor to be broken and deionized therein. The flame andglowing gases that appear as a result of the are burning fall into thefiameextinguishing grid 9 wherein they are subject to intensive cooling.

The provision of flame-extinguishing grids largely limits the ionizedspace beyond the arcing suppressors chambers, which is of primaryimportance for reducing the dimensions of the distributing devices.

Concurrently with the turn of the movable part 15 of the series coilused as a current limiter, the maximum current release gear 4 becomesoperable to actuate the control mechanism 2 which is quick to respondand which, in its turn, withdraws the contact holders 11 keeping themseparated so as to ensure a preset clearance between the contacts 10 and20.

The handle 3 occupies the position D.

During the operation of the control mechanism 2 the movable part 15 ofthe series coil used as a current limiter remains in a turned position(FIG. as a result of the current flowing through it, as long as the arcexist. After the suppression of the arc, the movable part 15 of theseries coil returns to the initial position under the action of thespring 31, the contact holders 11 being in a withdrawn position (FIG.1).

In case emergency current is induced in the circuit protected by theautomatic breaker, which is weaker than the current of theelectrodynamic setting of the series coil used as a current limiter,only the maximum current release gear 4 becomes operable. The movablepart 15 of the series coil functions only as a stationary contact. Asfor the rest, the process of automatic disconnection is similar to thatdescribed hereinabove.

Unlike the current-limiting version of the automatic breaker, theselective automatic breaker makes it a condition that its contacts incase of strong currents be closed within a preset time, i.e., prevent anelectrodynamic discard caused by the forces of current line narrowingsin an area of their convergence in the contact point of the workingcontacts. This condition is feasible owing to the use of the series coilas a compensator. In addition, the stationary part 16 of said coilshould be turned as is shown in FIG. 3. The flow through this coil isstrong currents results in the emergence of electrodynamic forcestending to turn the movable part 15 of said coil toward a pointer L(FIGS. 7a and 3), thus biasing the working contacts 20 against thecontacts 10 and preventing them from breaking until the preset period oftime elapses.

As soon as the preset period of time elapses, the maximum currentrelease gear 4 becomes operable actuating the control mechanism 2 whichwithdraws the contact holders 11. Further on, the breaking process goeson similar to that described hereinabove.

In case of the employment of the device 34 (FIGS. 5 and 6), theautomatic lowering of the working contacts of the automatic breakerwithout reducing the switching capacity is conditioned by the fact thatthe flow of strong currents through the series coil used as acompensator, its movable part 15 may turn toward the pointer L until theclearance 6, is fully used up, withdrawing from the rod 35.Simultaneously, the spring 28, in addition to effecting contact pressureon the current-conducting axis 27, returns, with the automatic breakerdisconnected, the movable part 15 of the series coil to the initialposition, pressing it to the rod 35. The moment created by the spring 28in relation to the current-conducting axis 27 is far less than themoment created by the spring 36. When the automatic breaker with thedevice 34 is engaged the control mechanism 2 overcomes the strain of thespring 36 only at a travel length equal to the clearance 5 correspondingto the normal lowering of the working contacts.

The device is particularly effective if the lowering of the breakercontacts becomes smaller in the course of its operation, say, at theexpense of the wear of the working contacts 10 and 20, as well as theWear of the parts of the control mechanism 2. Consequently, theprovision of the device 34 increases the dependability and prolongs theservice life of the automatic breaker.

The switching position of said automatic breaker is determined byadjusting the handle 3 (FIG. 1).

When the automatic breaker is in ON-position, the handle 3 occupies theposition C; if said breaker is disconnected manually, the handle is inthe position K. The position D indicates the automatic disconnection ofthe breaker.

In order to engage the automatic breaker after it has been automaticallydisconnected, it is necessary first to withdraw the handle 3 to theposition K, wind up the control mechanism 2 and then transfer the handleto the position C.

Thus, the proposed automatic breaker has small overall dimension and canbe manufactured from analogous members both in the current-limiting andselective versions.

In the current-limiting version said automatic breaker insures quick andreliable action while in the selective version its advantage is highelectrodynamic stability of the working contacts.

The present automatic breaker insures reliable protection againstoverloads and short circuits in powerful electric circuits (grids),permitting direct manual and remote control and is prepared for repeatedengagement after disconnecting short-circuit currents.

All this indicates essential advantages in the course of manufacturingthese automatic breakers and the use thereof.

We claim:

1. An automatic breaker comprising movable contact means and stationarycontact means operatively associated with one another, said stationarycontact means being constituted as a series coil including a pluralityof turns and serving as electrodynamic means and further including amovable and a stationary member, said stationary member acting to exertelectrodynamic forces on said movable member, said stationary memberbeing adjustably supported to be selectively turned from a firstposition to a second position 180 from said first position, whereby theextent of said electro-dynamic forces exerted by said stationary memberon said movable member is selectively altered, said stationary memberwhen in said first position acting to constitute said series coil as acurrent limiter and when in said second position acting to constitutesaid series coil as a compensator.

2. An automatic breaker as claimed in claim 1, wherein the movable andstationary members of the series coil are U-shaped and interconnected,such that the point of connection is between the sides of the U-shapedstationary member of the coil.

3. An automatic breaker as claimed in claim 2, wherein the point ofconnection of the U-shaped movable and stationary members of the seriescoil is equidistant from the sides of the U-shaped stationary member.

4. An automatic breaker as claimed in claim 1, wherein to increase theelectrodynamic impact on the movable member of the series coil, one ofthe sides of the latter is arranged inside the stationary member of theseries coil, while the other is extended outwardly therefrom.

5. An automatic breaker as claimed in claim 1, wherein the movablemember of the series coil includes an elongated end portion constitutingan arcing horn.

'6. An automatic breaker as claimed in claim 1, wherein the stationarymember of the coil includes a lead-out portion symmetrical to its sides,and adapted for being fastened in the breaker.

7. An automatic breaker as claimed in claim 1, wherein the movablemember of the series coil includes at least two spaced longitudinalportions and a contact element connected to each of said spacedlongitudinal portrons.

-8. An automatic breaker as claimed in claim 7, wherein said spacedlongitudinal portions are mechanically interconnected by means of aroller.

9. An automatic breaker as claimed in claim 7, including an arcing hornconnected to each said spaced longitudinal portions and wherein topreclude the interwelding of the arcing horns when moving towards eachother, said horns include projections arranged below the workingsurfaces of the horns to be engageable with one another.

10. An automatic breaker as claimed in claim 1 including adjustablemeans for adjusting the contact pressure between said movable contactmeans and said stationary contact means, said adjustable meanscomprising a bushing secured to said breaker, a rod including oppositeend portions, one of which is a head shiftably extending into saidbushing, a nut adjustably secured to the other end portion of said rod,and a spring engaging said nut and said bushing, said other end portionof said rod being engageable with said movable member of said stationarycontact means.

References Cited UNITED STATES PATENTS 3,092,699 6/1963 Latour 335'1953,127,488 3/1964 Bodenschatz 335- 16 3,277,407 10/1966 Kobayasi 200-147X3,420,971 1/1969 Aupetit 20 0-147X FOREIGN PATENTS 534,048 12/1954Belgium 335147 1,259,118 3/1961 France 33516 46,194 1960 Poland 335--16ROBERT K. SCHAEFER, Primary Examiner R. A. VANDERHYE, Assistant ExaminerU.S. Cl. X.R. 200-147; 335-16

